Take the quest Lab Space from Lork. It will lead you to Rata Sum. On your way there, consider making a little detour to advance Renk's quest chain (see below) or to unlock Tarnished Haven. Either way, completing Lab Space will directly lead to The Elusive Golemancer, gaining the support from Oola.

Acquiring Renk:

Take the quest A Little Help from Plaxx. As mentioned above, the first objective can be completed on your way to Rata Sum. The remaining objectives can only be completed after recruiting the other two Asura, making Renk the final addition to your krewe.

"These new golems will be invaluable in defending against the Destroyers. We will continue to refine them, and be willing to help you! Please give the bookahs, I mean humans, at your Eye of the North our warmest support."